For all the talk about food sustainability, we still lack a coherent, quantitative analysis of specific steps that can take a significant bite out of GHG emissions in the food sector. Labels like organic production and local food generally attract a lot of interest. These methods do indeed have environmental and social benefits, but their emissions reduction potential (on a large enough scale and a long enough time frame) appears to be modest at best. What is largely missing here is a full life-cycle perspective.
Looking beyond agriculture, food processing, packaging and landfilling may all have some emissions reduction potential. However, the one big opportunity that has generally been overlooked is the massive amounts of waste in the US food system.
Data from the USDA shows that food waste at the retail and consumer levels can be as low as 15% or as high as 55% depending on the commodity. In particular, a high proportion of perishable foods is not actually consumed and ends up as waste. A review of the leading culprits reveals an interesting story.
Considering only the commodities most heavily consumed in the US – some meats (beef, pork, chicken), dairy (mainly fluid milk products), eggs, grains, fresh vegetables and fresh fruits – our preliminary analysis shows that an average of 39% of these commodities are wasted at the retail and consumer levels. The wasted food in these categories adds up to an annual total of 47 MMT (million metric tonnes). The GHG implications of this waste are significant: approximately 103 MMT CO2e per year from the production and processing of that wasted food, plus an estimated additional 15 MMT CO2e from landfilling (with assumptions about flaring and methane capture) and around 6 MMT CO2e from transport to retail. This analysis leaves out a few other emissions related to the waste (such as food packaging and the home/institutional cooking energy that can be attributed to food wasted after cooking), as well as many other food commodities that are consumed in smaller quantities.
In total, the life-cycle GHG emissions from wasted food appear to be at least 125 MMT CO2e per year, and are possibly higher than this estimate. Let us put this in context. A recent publication from the Product Policy Institute (which builds on an EPA publication) reports that the provision of food (accounting for imports and exports) contributes 12% of US GHG emissions, or 902 MMT CO2e annually. Thus, food waste likely accounts for something like 14% or more of the food-related emissions. For example, if the food waste could be cut in half, and assuming that production is adjusted to match consumer demand, then at least 7% of the food-related emissions (~63 MMT CO2e) could be removed from the system. More aggressive targets would yield higher reductions in emissions. The nice thing about reducing waste is that the savings are not just one-time – the emissions reduction continues year after year as long as we keep a lid on the waste.
There is no doubt that this will require a large national effort – ideally with government and the food industry working together – to educate consumers and institutions on better food preservation techniques. We should be able to do a lot with existing technologies, and making this a national priority could spur further development of innovative (meaning low cost and low carbon) packaging and food preservation technologies.
We would certainly want to have some slack in the food system so that unexpected drops in production in a particular region can be compensated by production from other regions. We also have an obligation to provide sufficient food security to everyone. The urgent need to reduce GHG emissions must be balanced against these requirements. For example, a portion of the potential emissions reduction could be traded off in return for the ability to route the surplus food to the hungry in this country and elsewhere. Some of the agricultural land that is used today to produce the surplus food could instead grow sustainable feedstocks for next-generation biofuels. (I will save the inevitable policy discussions for another post.)
Food waste is not just a US problem. In India – where 63% of children reportedly go to bed hungry every night – a quarter of the agricultural produce is lost due to inadequate storage and distribution networks. The waste percentages are below US levels but still surprisingly high: 7% of grain and over 30% of fruits and vegetables. The opportunity in countries like India is to improve nutrition and food security with the existing food supply.
We should begin to think of GHG emissions as a form of currency: we can use them for productive purposes, such as providing sufficient food and fuel for the whole population, but emissions that do not serve a useful purpose are expenses that should be targeted for reduction.